CNC Machines Information

Mounted directly on machine frame next to motor, X67 Stepper Motor Modules offer 2 control possibilities and integrated motor detection. Module X67SM4320 controls up to 4 stepper motors, with rated voltage of 18-30 Vdc at motor current up to 1 A, while module X67SM2436 controls up to 2 stepper motors, with rated voltage of 18-48 Vdc at motor current up to 3 A. It also has 6 digital inputs. Both offer 20 kHz max step frequency and stall detection.

B&R X67 Stepper Motor Module

Controlling stepper motors with IP67 protection
The new B&R X67 Stepper Motor Modules provide machine builders a more cost effective solution to controlling stepper motors. Stepper motors are still very popular among machine builders for various reasons including: high degree of torque, operation without feedback, and holding the last position when power is disconnected just to name a few of the special features of the stepper motor. The X67 stepper motor module is available in two variants based on the customer's requirements. The highlights of the new X67 stepper motor modules can be summarized as follows:

* Integrated motor detection

* 64 microsteps

* Stall detection

* Extremely compact

* IP67 protection

Two performance classes with IP67 protection
The stepper motor module X67SM4320 is used to control up to four stepper motors with a rated voltage of 18-30 VDC at a motor current up to 1 A (1.5 A peak). The maximum step frequency is 20 kHz. The second stepper motor module variant X67SM2436 is used to control up to two stepper motors with a rated voltage of 18-48 VDC at a motor current up to 3 A (5 A peak). The maximum step frequency is also 20 kHz. Additionally, this module has six digital inputs that can be used as limit switches or as encoder inputs. Both variants are ground-breaking in their compact design. Because of their IP67 protection the modules can be mounted directly on the machine frame right next to the motor. Advantages include reduced space requirements and lower thermal loads in the switching cabinet as well as less wiring. With an input voltage range of up to 48 V, peak performance can be achieved in the range of 200 W.

Technical Data

The X67 Stepper Motor modules offer the following two control possibilities: Either using position settings from the B&R Soft NC or Soft CNC. The current position values can be checked cyclically by the PLC and be reacted to using the control program.

Microstepping

Conventional stepper motors usually have a stepping angle of 3.6 to 0.9 degrees. Although this is sufficient for many positioning tasks, a more exact division is frequently necessary. At this point, it's currently not technologically feasible to reduce the stepping angle of the stepper motor indiscriminately. Besides that, each additional gradation increases the cost of the motor considerably.

The microstepping solution

By dividing the current in the coils, just about any division can be achieved for the stepping angle. This doesn't just increase the positioning accuracy; the micro steps also result in smoother operation. Other measures for reducing resonance are no longer necessary.

Automatic microstep adjustment

Depending on the step frequency, the module always carries out the maximum number of possible microsteps. The internal current controller works with a maximum frequency of 40 kHz, which also makes it possible to reach a frequency of 20 kHz in half-step mode.

On a motor with a 1.8 degree stepping angle, the result is 3,000 rpm, which is generally more than sufficient for conventional applications.

Configurable motor current

By individually adjusting the coil currents, the motor is only operated with the current it actually needs. This simplifies the selection of the available motors and prevents unnecessary heating. Because the latter reduces the energy consumption and thermal load, the effects are positive on the lifespan of the entire system.

Complete flexibility is achieved by using the values for holding current, boost current and continuous current, which are completely independent of each other. The current for the microsteps is automatically adjusted to the configured current values.

Additional features

An enormous help is the automatic motor detection system at standstills. The stepper modules can identify the connected motors using their coil characteristics and generate feedback in the form of an analog value. This makes it possible to detect not only wiring errors, but incorrect motor types being used mistakenly as well.

A stall detection mechanism is integrated to analyze the motor load. The stall is recognized using a configurable threshold. This allows an overload or motor standstill to be detected precisely in many different types of applications.

http://findarticles.com/p/articles/mi_m0PIL/is_2006_June_26/ai_n16499665

Having invested in CNC automatics, a manufacturer of machined complex plastics parts has found it can take smaller batches and diversify into other areas.
Plastic turned components as small as half the size of a matchhead with an intricate and accurate profile and a central drilled hole for use by children with ‘glue-ear’ and PTFE insulators for fly-catchers used in restaurants, are typical of the sort of work Tefloturn pass through their citizen cnc sliding head automatic lathes. The company, which is based near to Hertford, has two Citizens, an L16 bought second hand from NC Engineering of Watford which has been followed up with a new B20. It processes a wide range of plastic materials including PTFE, PEEK, nylon, acetal and other ‘engineering’ plastics in quantities from a single component to batches of 250,000.

Customers include electronics, medical, steam management and bearing manufacturers.

Managing Director Mick Finney describes how accuracy and repeatability of tolerances can be quite tight especially given the properties of the materials being machined.

‘Bore tolerances of +/-0.025mm often apply while the general machining tolerance is +/-0.050mm.

Likewise, surface finish is usually very important while the degree of complexity of some parts can be considerable,’ he says.

He describes how medical applications especially demand high finish and total freedom from burrs which demand good machine and setting techniques.

‘We also make a lot of plain rings and seals and there is a large demand for threads, knurling and some cross-drilling and slotting on plastic turned parts,’ he says.

Tefloturn was formed in the mid-1990s on the back of a pair of cam actuated sliding head machines.

By 1998, however, the company had reached the limits capable from these machines and started to look for a more flexible solution.

‘We couldn’t afford a new sliding head machine at that time,’ Mick Finney admits, ’so we approached a couple of suppliers to try and source a good secondhand machine.

‘NC Engineering came back to us quite swiftly with our L16, which was already five years old and since it was installed it has proved to be a very good buy.

Reliability has been very good and NC’s back-up in terms of both training and service/maintenance has also been above reproach.’ ‘One of the first components we ever machined on the L16 required multiple operations, and we could never produce more than 30 an hour.

When the L16 was set up, the part was turned complete in a single operation in under 28 seconds.

Now that was a massive increase in productivity for us,’ Mick Finney maintains.

The combined performance of the machine and support by NC Engineering paved the way for Tefloturn to select a larger capacity five-axis Citizen B20 which was justified against one particular contract.

However, the additional capabilities with 10,000 revs/min spindle, 12 tools and extended unmanned running with an improved accuracy has been the catalyst to draw in even more work.

‘Accuracy and consistency are much easier to maintain on the Citizen B20, and it’s also much faster than the L16,’ Mick Finney admits.

‘Availability of an additional powered tool station means that its second operation capabilities are extended.

Together with a conventional CNC lathe, which we bought in between, the citizen machines provide us with the ability to supply exactly what any customer wants up to 300mm diameter.’ Although virtually all of the plastic materials processed by Tefloturn are free machining, the company always uses coolant to help maintain stable temperatures and overcome the influence of thermal growth which is significantly greater than with metals.

And although most materials can be machined using high speed steel, some of the more abrasive ‘filled’ materials have to be cut using carbide.

‘Machining plastics is quite a specialised business,’ says Mick Finney, ‘but the Citizen machines have allowed us to apply our knowledge across a wider range of work.

With the B20 we have the option of lights-out running, something that we’ve never had before.

Although some plastics cause a problem due to swarf and have to be overseen, those jobs where we can use the unmanned capability, make a huge difference to our manufacturing efficiency.

We have also found on short batch work we can program, set the machines and produce the parts in less time than it would take us to perform a cam change on one of the old machines.’ Mick Finney describes how the Citizens have made a very big difference to the way Tefloturn works.

‘When we had the cam machines, if we hadn’t got a suitable cam set, then we couldn’t make a part unless the volume was either very small, or large enough to justify commissioning a new set of cams.

That meant that we had to turn away quite a lot of small to medium volume business.

We also had a substantial amount of work that required secondary operations and it was rare to be able to complete a job in one set-up.’ ‘Investing in the Citizen machines has certainly allowed us to move the company forward quickly.

Our minimum batch quantity is now much smaller while the level of component complexity that we can competitively handle is so much higher.

This has allowed us to diversify the business along lines that we would never have thought possible before,’ he says.


http://www.cncmachinesinfo.com/articles/category/cnc-stepper-moter/

Advanced Micro Controls (AMCI), a Connecticut based industrial controls company, has developed a novel stepper motor control module for Allen-Bradley's Point I/O. Boasting seamless integration into Allen-Bradley's distributed I/O network, the 3401 module is ideal for applications where low-cost of ownership are key for successful control system design and operation. Exploring the module's other benefits, Sales Manager Leo Brennan explains: 'The 3401 has the lowest per axis cost of all the motion control modules available for Allen Bradley PLCs'.

'We found customers were looking for a motion control solution that provided all of the functionality of a standard motion controller but had some of the cost advantages of the Point I/O system'.

'AMCI responded by designing the 3401'.

'The unique design of the Point I/O system allows the I/O to be distributed throughout the machine instead of being located in one central panel'.

'This provides overall savings in wiring and can lead to a more modular machine design'.

The 3401 Point I/O card marks AMCI's fifth stepper motor controller module solution for Allen Bradley PLCs.

When asked how AMCI is able to develop so many integrated PLC module solutions, Sales Engineer Matthew Tellier stated: 'As the original third party supplier with Rockwell Automation, AMCI's long standing partnership with Allen Bradley enables our company to quickly engineer solutions for new platforms, providing a more complete control system for our customers'.

'This close relationship guarantees a finished product that is 100% compatible with Allen Bradley PLCs for true plug and play functionality'.

AMCI's 10 years of experience in developing stepper modules has led to an efficient programming structure that capitalises on user-friendly commands that are simple to implement.

A relative move, absolute move, or a manual move can be executed with just one rung of logic.

Additionally, the 3401 module has two sinking inputs, which can be used for homing and limit switch operations, and step and direction output signals that interface to any of AMCI's SD stepper drives or the recently released SMD family of integrated stepper drive/motor packages.

By using standard output signals, the 3401 module can also integrate with other manufacturers' stepper drives and even servo systems, such as the Allen Bradley Ultra series of drives that can be controlled by step and direction signals.


http://www.engineeringtalk.com/news/amn/amn104.html